numerous Chinese manufacturers offer Light Blocking Effect Testing Machines, primarily for textiles (curtains, fabrics) to measure shading performance (like the M112 model), using photometers to compare light transmission with and without the sample, with options for touch screens, printers, and compliance with standards like AATCC 148. You can find these on B2B platforms like Made-in-China.com and Alibaba, from suppliers like UTSTESTER, GBPI, and Hongjin, offering features like automated results, custom settings, and competitive pricing. 

When searching, use terms like "Light Blocking Tester," "Fabric Shading Tester," "Light Transmittance Tester," or specific models like "UTSTESTER M112" on Chinese B2B sites.